Chip resistors are also known as surface mount devices. They are IC devices that are designed in rectangular and square chip packages. But what are resistors? Well, these are components that are known to oppose electric current flow.
They are mostly used to protect, control and operate circuits. Sometimes they do have a fixed resistance value. While other times they can be adjusted within a specific range. Chip resistors, in particular, make up the foundation of lots of current electronic devices. They are mostly surface mount devices (SMDs). This is because they have no lead components and are mounted directly on top of a printed circuit board.
As earlier stated, they are designed in shapes of squares and rectangles, and their power ratings depend on the length and width of the device. Surface-mount resistors are seen in a wide variety of sizes. Some of the sizes are, in fact very little, and difficult to handle. They are also available in common values like E3 and E192. You can also find them in other particular values only if these values are needed.
Surface-mount chip resistors are just one component that makes use of surface mount devices. And, this component as already stated, is now a foundation for manufacturing electronic equipment. This is because it allows for much faster and effective construction of electronic printed circuit boards.
The summary here is that chip resistors provide plenty of benefits for the mass production of electric devices. They may use several technology or construction types. And each of them has its own significant advantage and disadvantage. Below are some of the common listed types:
Thick Film Resistor
These are formed by applying a resistive metallic paste. This paste is applied onto a base. What they do is to provide a high resistance per area. They cost way less compared to similar technologies like wire-wound devices.
Although their frequency response is identical to thin-film devices and foils, they are much noisier. Despite their limitations, they are very well used in circuit sections. Also, they require less precision and durability.
This banks on the deposition of a thin metallic coating. And this coating is laid on top of a ceramic substrate. This particular device features a high level of resistance per given location. This makes them economical. It also makes them space-efficient.
However, they have certain limitations. For example, its film is susceptible to failure. This is a result of elevated temperatures, chemical contamination, and water vapour. You can check here for more on thin-film technology.
This is made up of metallic foil. It is applied to a ceramic substrate that has been photo-etched with a resistive pattern. This then forms a resistor that has an excellent characteristic of being highly stable. It has low capacitance, less noise, and has non-inductance as well. It achieves this feat without sacrificing speed and accuracy.
How Are Chip Resistors Made?
Chip resistors or surface mount devices are created by pacing end connection electrode bases onto a ceramic substrate. Afterwards, the resistor is then fired. This is to make sure the electrodes are perfectly firm. Afterwards, a resistive material’s film is deposited or printed. And then, the resistor is again fired.
Later, the resistor is covered with consecutive layers of a protective coat. The coats do dry between applications. All the layers are meant to ensure that mechanical damages are avoided. It also ensures that moisture and other contaminants are prevented.
Lastly, if the resistor’s surface is large enough, it is placed with a marking. They are then packaged to look like blister rolls. This is to be used on pick and place machines.
How Do You Read the Code of a Chip Resistor?
Because these are small mounted devices, they are marked with about three- or four-digit codes. These are called SMD Resistor Codes. The codes indicate their resistance value.
When it’s a three-digit code, the first two digits tell you the significant resistance number. The third digit is often a multiplier that will multiply the first two digits. Whereas for four-digit numbers, the first three are the significant numbers, with the last being the multiplier.
What Are the Advantages of SMDs?
There are lots of advantages of SMDs. One is that they are of diminutive sizes. They have a much higher component density as they have more connections for every component. They are a much faster and simpler automated assembly.
Furthermore, they are structured, so fewer holes are bored into a PCB (Printed Circuit Board). They are also placed on both sides of a PCB. They do have enhanced mechanical performance under certain conditions like vibration and shock. And have many relatively cheap parts.
Are there Disadvantages of SMDs?
SMDs do have a few disadvantages. They do have solder components that are vulnerable to damages. And this can occur when potted compounds move through thermal cycling. They also have component packages that cannot be installed in sockets. Also, when components get damaged or need reassembling, it needs to be done by an expert hand.
It also requires more extensive tools. In addition, SMDs, have a tiny surface area for marking. This then means that component values and part ID codes will be more cryptic and smaller.
Finally, SMDs cannot be used directly with plug-in breadboards. They need a custom PCB for each prototype. Or, the SMD can be mounted on a pin-leaded carrier.
Chip resistors are also termed surface mount devices. SMDs are typically electronic commonest meant to be used with SMTs (Surface Mount Technology). SMTs were formed to meet consumer needs for printed circuit boards manufacturers to make use of smaller components that are cheaper, faster, and more efficient. SMDs are a lot smaller than through-hole resistors.
While others require wire leads to go through PCBs, SMDs have terminations soldered to pads. These pads are on the surface of the PCBs, with these holes and no longer in the boards. This allows for both sides of the PCBs to be fully used.